When reading a paper by Richard Lindzen Climate Science: Is it currently designed to answer questions? I was struck by some comments towards the end by John P. Holdren, director of the Woods Hole Research Center about climate skeptics. He says:

First, they have not come up with any plausible alternative culprit for the disruption of global climate that is being observed, for example, a culprit other than the greenhouse-gas buildups in the atmosphere that have been measured and tied beyond doubt to human activities. (The argument that variations in the sun’s output might be responsible fails a number of elementary scientific tests.)

Second, having not succeeded in finding an alternative, they haven’t even tried to do what would be logically necessary if they had one, which is to explain how it can be that everything modern science tells us about the interactions of greenhouse gases with energy flow in the atmosphere is wrong.

As to the first point, most skeptics have been maintaining that similar Arctic conditions were experienced recently, that the current climate state is similar to the Medieval Warm Period, and possibly temperatures have exceeded the present throughout the recent geologically warm 10,000 years called the Holocene. These issues as far as I know are still unsettled. Holdren is criticizing skeptics for not coming up with an explanation for a non-disruption that has not been observed.

OTOH, the record of alarmists of loudly proclaimed ‘disruptions’ that have subsequently been discredited provides numerous examples of scientific bias: that the climate system is ‘more sensitive than we thought‘, that the intensity of hurricanes and others storms are increasing, that droughts and floods are increasing, that the Walker circulation is weakening, a miserable record predicting Arctic ice extent, to name a few.

On his second point, skeptics have also “consistently affirmed modern science and interactions of greenhouse gases with energy flow in the atmosphere” by finding that the rate of underlying warming that can be attributed to increases in CO2 is consistent with the direct radiative effect of CO2, a paltry 0.05C/decade. The graph below lists some of the authors that have arrived at the same basic rate of warming through completely independent means (there are others as well such as Miskolczi and Nir Shaviv).

These sources of observational evidence suggest that the amount of warming will be 0.5C by 2100, not nothing, but not catastrophic and certainly well below the IPCC projections, produced by a chorus of climate simulations sharing many common aspects. The difference is due to the warming attributed to speculative and as yet unconfirmed positive feedbacks. Holdren tells us that:

the extent of unfounded skepticism about the disruption of global climate by human-produced greenhouse gases is not just regrettable, it is dangerous.

One of the main reasons for persistent skepticism is that people look at the evidence and find it wanting, they look at the AGW proponents and find misrepresentation of the alternative arguments, and they look at the emotional appeals and see bias. When people of science like RealClimate start worrying that their lack of results is due to being ‘unlikable’ and ‘poor communicators’, its my experience that the real problem is the use of subjective vehicles to back up inconclusive science. Skepticism is healthy, and the way for AGW proponents to further their work is through greater openness and objectivity, not stronger emotional appeals.